Not totally convinced
a) Another SAN. This time it is all ethernet, but that won't be routed through our regular switches, ergo another new SAN.
b) No filesystems. FS do offer benefits that kv stores can't. Snapshots, being able to browse, permissions, end-to-end checksumming...
c) No real difference over iSCSI or AoE and giving a raw block device to the kv store of your choice as backing storage.
d) Loss of bandwidth or ridiculously expensive adapters. Running this on GigE, you won't hit 125MB/s. Run on 10GigE, that will go up to about 1250 MB/s, and I'm not even including overheads here. Presumably you would have one, possibly two aggregated connections to the SAN switch, you're going to be hard pushed to even match the bandwidth in a single MiniSAS cable.
e) No mention of redundancy, which normally means if you want redundancy, store multiple copies on different disks. Eww.